CN115407241B - Secondary circuit grounding current monitoring system, method and computer readable storage medium - Google Patents
Secondary circuit grounding current monitoring system, method and computer readable storage medium Download PDFInfo
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- CN115407241B CN115407241B CN202211345812.0A CN202211345812A CN115407241B CN 115407241 B CN115407241 B CN 115407241B CN 202211345812 A CN202211345812 A CN 202211345812A CN 115407241 B CN115407241 B CN 115407241B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16504—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the components employed
- G01R19/16509—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the components employed using electromagnetic relays, e.g. reed relay
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention disclosesA secondary circuit ground current monitoring system, method and computer readable storage medium are provided. The invention provides a secondary circuit grounding current monitoring system, comprising: control module, voltage sampling module, current sampling module, control circuit, current transformer, normally closed contactor and test resistor R j . According to the invention, the resistance switching circuit is added to the secondary circuit grounding point, and the resistance switching circuit can control the test resistance R through the opening and closing of the normally closed contactor j And if the secondary circuit is connected, calculating the capacitive current of the grounding point of the secondary circuit when the normally closed contactor is disconnected, judging the grounding fault by comparing whether the current of the grounding point is greater than the capacitive current, and avoiding the leakage judgment of the multi-point grounding fault when the current is less than 50mA.
Description
Technical Field
The invention relates to the technical field of circuits, in particular to a secondary circuit grounding current monitoring system and method and a computer readable storage medium.
Background
The secondary circuit of the transformer substation is a low-voltage and low-current circuit formed after passing through a voltage transformer and a current transformer. The secondary circuit plays a role in measuring, protecting the primary circuit and the like, so that the reliability of the secondary circuit is related to the normal operation of the power grid. In order to avoid insulation breakdown and ensure the safety of equipment and workers of the secondary circuit, the secondary circuit must be provided with one point and only one point is grounded. When two or more points of the secondary circuit are grounded, voltages between different grounding points are applied between the grounding points of the secondary circuit due to a certain potential difference of the ground. The two-point grounding voltage can increase the measurement error of the secondary loop current and the voltage, and can cause protection misoperation or failure operation in serious conditions, thereby seriously influencing the safe operation of a power grid.
When one point of the secondary loop is grounded, the grounding point has no current or little induced current. The secondary circuit grounding current means that when a multipoint grounding fault occurs, the earth voltage forms a circuit through a plurality of grounding points, and current is formed on the original grounding points. Therefore, the staff often judges whether the secondary circuit has multiple ground fault through measuring original earth point electric current, and concrete mode includes: manual measurement and real-time monitoring. And manually measuring the current of the secondary loop grounding point by adopting an ammeter, judging that the multipoint grounding fault exists if the current of the grounding point is greater than or equal to 50mA according to the relevant regulations of the power grid, and otherwise, judging that the multipoint grounding fault is normal. The real-time monitoring is that the current of the secondary loop grounding point is monitored in real time through point-to-device and a current transformer, and when the current of the secondary loop is more than or equal to 50mA, an alarm signal is sent to an upper computer, so that the real-time fault monitoring effect is realized.
However, the secondary circuit is complex and long in line, and has a certain distributed capacitance to ground, and the distributed capacitance also forms current to ground and returns to the power supply end through the original grounding point, so that the manual measurement takes more than or equal to 50mA as the judgment basis of multipoint grounding. However, in some newly built systems with small secondary loops, the current caused by multipoint earthing may not exceed 50mA because the induced current is small and the potential difference of the earth is small. At this time, the above two methods cannot effectively monitor the multipoint ground fault. In summary, the prior art cannot distinguish whether the current of the original grounding point is a capacitive current or a current formed by multipoint grounding, so that a leakage judgment is generated when multipoint grounding exists but the current does not exceed 50mA.
Disclosure of Invention
The invention aims to provide a secondary circuit grounding current monitoring system, a method and a computer readable storage medium, which aim to solve the problem that the prior art cannot distinguish whether the current of an original grounding point is capacitive current or current formed by multipoint grounding, so that leakage judgment is generated when the current is not more than 50mA and the current is multipoint grounded.
The invention provides a secondary circuit grounding current monitoring system, comprising: control module, voltage sampling module, current sampling module, control circuit, current transformer, normally closed contactor and test resistor R j (ii) a The voltage sampling module, the current sampling module and the control circuit are respectively connected with the control module, and the voltage sampling module is connected with the phase A of the secondary loop through a port A; disconnecting the original grounding point of the secondary circuit, and connecting the original grounding point of the secondary circuit by the device through an N interface; the device is connected with the ground through a GND port; the normally closed contactor is connected between the GND port and the N interface, the current transformer is arranged on a line between the GND port and the N interface, and the test resistor R j Is connected with the normally closed contactor in parallel;
the voltage sampling module is used for collecting the voltage between the phase line of the secondary circuit and the ground, converting the voltage into an analog signal and sending the analog signal to the control module;
the current transformer is used for measuring the current of the secondary loop grounding point;
the current sampling module is used for converting the measurement signal of the current transformer into an analog signal and then sending the analog signal to the control module;
the control circuit is used for controlling the switch of the normally closed contactor according to the signal sent by the control module;
the normally closed contactor is used for being disconnected once every other set time t under the control of the control circuit or when a grounding current I a Once disconnected when changed;
the control module is used for calculating the voltage U of the secondary circuit to the ground according to the signal sent by the voltage sampling module when the normally closed contactor is closed d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1 ；
And, when the normally closed contactor is opened, the grounding current passes through the test resistor R j Then, the grounding current I is calculated according to the signal sent by the current sampling module b Phase Q of 2 (ii) a According to the voltage U of the secondary loop to the ground d Earth current I b Phase Q of 2 Testing resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 (ii) a Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1 (ii) a If the current to ground is I a Capacitive current I greater than secondary loop ground 1 And judging that the secondary circuit of the circuit has a ground fault.
Further, each opening time of the normally closed contactor is 0.5s.
Further, the resistance R is tested j Is a 1k omega resistor.
Further, the control module is used for calculating the capacitive current I of the grounding point in the following way 1 ：
In the formula I 1 Capacitive current as earth point, U d Is the voltage of the secondary loop to ground, Q 2 To ground current I b Phase of (2), R j To test the resistance.
Further, the control module adopts an STM32F407ZGT6 control chip of an ideological semiconductor.
Further, the secondary circuit ground current monitoring system further includes: and the touch display module is connected with the control module and is used for displaying the grounding current and the fault signal and setting, recording and checking parameters of the device.
Further, the secondary circuit ground current monitoring system further includes: the communication module is connected with the control module and used for sending grounding current I to the upper computer a The value of (3) to realize the function of monitoring the current of the secondary loop grounding point in real time; and sending a fault signal to the upper computer to realize a fault warning function.
The invention provides a secondary circuit grounding current monitoring method, which is applied to the secondary circuit grounding current monitoring system and comprises the following steps:
acquiring a signal sent by a voltage sampling module and a signal sent by a current sampling module, wherein the signal sent by the voltage sampling module is an analog signal of voltage between a phase line and ground of a secondary circuit, and the signal sent by the current sampling module is an analog signal of current of a grounding point of the secondary circuit;
sending a signal to a control circuit to control the normally closed contactor to be disconnected once every set time t or when the grounding current I is generated a Once disconnected when changed;
when the normally closed contactor is closed, the voltage U of the secondary circuit to the ground is calculated according to the signal sent by the voltage sampling module d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1 ；
When the normally closed contactor is opened, the grounding current passes through the test resistor R j Then, the grounding current I at the moment is calculated according to the signal sent by the current sampling module b Phase Q of 2 ；
According to the voltage U of the secondary loop to the ground d The grounding current I at this time b Phase Q of 2 Testing resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 ；
Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1 ；
If the current to ground is I a Capacitive current I greater than secondary loop ground 1 And judging that the secondary circuit of the circuit has a ground fault.
The present invention provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described secondary circuit ground current monitoring method.
According to the above technical solution, the present invention provides a secondary circuit ground current monitoring system, method and computer readable storage medium, wherein a resistance switching circuit is added to a secondary circuit ground point, and the resistance switching circuit can control a test resistor R through the opening and closing of a normally closed contactor j And if the secondary circuit is connected, calculating the capacitive current of the grounding point of the secondary circuit when the normally closed contactor is disconnected, judging the grounding fault by comparing whether the current of the grounding point is greater than the capacitive current, and avoiding the leakage judgment of the multi-point grounding fault when the current is less than 50mA.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of a secondary circuit ground current monitoring system provided by the present invention;
FIG. 2 is a schematic diagram of secondary loop capacitive current generation;
FIG. 3 is an equivalent circuit diagram of a schematic diagram of the capacitive current generation of the secondary loop;
fig. 4 is a schematic diagram of secondary loop capacitive current calculation.
Illustration of the drawings: 1-a touch display module; 2-a control module; 3-a voltage sampling module; 4-a current sampling module; 5-a communication module; 6-a control circuit; 7-a current transformer; 8-normally closed contactor.
Detailed Description
Referring to fig. 1, an embodiment of the present invention provides a secondary circuit ground current monitoring system, which includes a touch display module 1, a control module 2, a voltage sampling module 3, a current sampling module 4, a communication module 5, a control circuit 6, a current transformer 7, a normally closed contactor 8, and a test resistor R j 。
The touch display module 1, the voltage sampling module 3, the current sampling module 4, the communication module 5 and the control circuit 6 are respectively connected with the control module 2. The voltage sampling module 3 is connected with the phase A of the secondary loop through a port A; the original grounding point of the secondary loop is disconnected, and the device is connected with the original grounding point of the secondary loop through the N interface. The device is connected to ground through the GND port. A normally closed contactor 8 is connected between the GND port and the N interface, a current transformer 7 is arranged on a line between the GND port and the N interface, a test resistor Rj is connected with the normally closed contactor 8 in parallel, and a test resistor R is connected with the normally closed contactor j Is a 1k omega resistor.
The voltage sampling module 3 is used for collecting the voltage between the phase line of the secondary circuit and the ground, converting the voltage into an analog signal and sending the analog signal to the control module. The current transformer 7 is used for measuring the current of a secondary circuit grounding point, the current transformer 7 is connected with the current sampling module 4, and the current sampling module 4 is used for converting a measuring signal of the current transformer 7 into an analog signal and then sending the analog signal to the control module. And the control circuit 6 is used for controlling the on-off of the normally closed contactor according to the signal sent by the control module 2. The normally closed contactor 8 is used for being disconnected once every set time t or when the grounding current I is generated under the control of the control circuit a And is disconnected once when a change occurs. Specifically, the normally closed contactor 8 is opened for 0.5s each time.
The control module 2 adopts an STM32F407ZGT6 control chip of an ideographic semiconductor and is used for calculating the voltage U of a secondary circuit to the ground according to a signal sent by the voltage sampling module when the normally closed contactor is closed d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1 . When the normally closed contactor is opened, the grounding current is measuredTest resistor R j Then, the grounding current I is calculated according to the signal sent by the current sampling module b Phase Q of 2 (ii) a According to the voltage U of the secondary loop to the ground d The grounding current I at this time b Phase Q of 2 And a test resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 (ii) a Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1 (ii) a If the current to ground is I a Capacitive current I greater than secondary loop ground 1 And judging that the secondary circuit of the circuit has a ground fault.
The touch display module 1 is used for displaying grounding current and fault signals, and setting, recording and checking parameters of the device. The communication module 5 is used for sending grounding current I to the upper computer a The current monitoring function of the secondary loop grounding point is realized; and sending a fault signal to the upper computer to realize a fault warning function.
Therefore, the control module 2 calculates the capacitive current I of the grounding point by using the following formula 1 。
In the formula I 1 Capacitive current as earth point, U d Is the voltage of the secondary loop to ground, Q 2 To ground current I b Phase of (2), R j To test the resistance.
In this embodiment, the control module 2 calculates the ground current I according to the signal sent by the current sampling module b Phase Q of 2 (ii) a According to the voltage U of the secondary loop to the ground d Earth current I b Phase Q of 2 Testing resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 The principle of (1) is as follows:
as shown in fig. 2 to 4, since the secondary circuit has a long and complicated line distribution, the cable has a certain distributed capacitance to the ground, and the distributed capacitance has a certain leakage current flowing to the ground at the ac voltage and returning to the ground from the ground point. In FIG. 2, U a 、U b 、U c Three-phase voltage to earth of secondary circuit, C a 、C b 、C c The capacitance is distributed for three phases of the secondary loop to ground. FIG. 2 can be simplified to the equivalent circuit diagram, U, shown in FIG. 3 d For the voltage of the secondary circuit to ground, the secondary circuit has some relays, cables, etc. with inductive properties, L d Is the equivalent inductance of the secondary loop, C d The distributed capacitance of the secondary loop to the ground, R is the sum of the wire of the secondary loop and the ground resistance. The current formed by the loop is the capacitive current I 1 It measures its phase Q through the original earth point 1 And recorded.
Due to the capacitance C d The capacitive reactance of (a) is high, usually in the k omega level, and the secondary loop wire and ground resistance R is very small, usually less than 10 omega, so that R can be ignored here. If a 1k omega test resistor R is connected to the original grounding point j Measuring the current I through the existing ground point at this time, as shown in FIG. 4 2 Phase Q of 2 。
Since R is small and negligible, I 1 The circuit formed is only L d And C d Thus its phase Q 1 Can be considered as pi/2. And I 2 The formed circuit has more test resistors R j According to the formula of the phase calculation of the series circuit, its phase Q 2 ：
In the formulafThe current frequency is 50Hz.
But a phase difference
：
The sum of the inductance in the secondary loop and the capacitance-to-ground impedance can be derived from equation (2):
thus, the capacitive current I 1 It can be calculated that:
the working principle of the secondary circuit grounding current monitoring system of the embodiment of the invention is as follows: during operation, the voltage U of the secondary loop to the ground is measured through the voltage sampling module d . Measuring ground current I by current sampling module and current transformer a And calculating the current I through the processing of the control module a Magnitude and phase Q of 1 And sending current I to an upper computer through a communication module a The value of (2) to realize the function of monitoring the current of the secondary loop grounding point in real time.
The normally closed contactor is opened once every set time t or when the current I is applied a When the normal closed contactor is switched off, the grounding current passes through the test resistor R j The control module collects the current I at the moment b Phase Q of 2 Calculating the capacitive current I of the grounding point by the formula (4) 1 Size.
When the control module calculates that the current of the secondary loop grounding point is larger than the capacitive current, I a Is greater than I 1 And at the moment, the control module sends a fault signal to the upper computer through the communication module to realize a fault alarm function.
The embodiment of the invention provides a secondary circuit grounding current monitoring method, which is applied to the secondary circuit grounding current monitoring system and comprises the following steps:
acquiring a signal sent by a voltage sampling module and a signal sent by a current sampling module, wherein the signal sent by the voltage sampling moduleThe current sampling module is used for sending a signal which is an analog signal of voltage between a phase line and ground of a secondary circuit, and the signal sent by the current sampling module is an analog signal of current of a grounding point of the secondary circuit. Sending a signal to a control circuit to control the normally closed contactor to be disconnected once every set time t or when the grounding current I is generated a Once disconnected when a change occurs.
When the normally closed contactor is closed, the voltage U of the secondary circuit to the ground is calculated according to the signal sent by the voltage sampling module d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1。 When the normally closed contactor is disconnected, the grounding current passes through a test resistor R j Then, the grounding current I at the moment is calculated according to the signal sent by the current sampling module b Phase Q of 2。
According to the voltage U of the secondary loop to the ground d The grounding current I at this time b Phase Q of 2 Testing resistor R j Calculating the capacitive current I of the secondary loop grounding point 1。 Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1。 If the current to ground is I a Capacitive current I greater than secondary loop ground 1 And judging that the secondary circuit of the circuit has a ground fault.
The present invention provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described secondary circuit ground current monitoring method.
The embodiment of the invention also provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program realizes part or all of the steps in the embodiment of the secondary circuit ground current monitoring method provided by the invention. The computer readable storage medium may be a magnetic disk, an optical disk, a Read-only memory (ROM) or a Random Access Memory (RAM).
Those skilled in the art will readily appreciate that the techniques of the embodiments of the present invention may be implemented using software plus any required general purpose hardware platform. Based on such understanding, the technical solutions in the embodiments of the present invention may be essentially or partially implemented in the form of a software product, which may be stored in a computer-readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments of the present invention. The same and similar parts in the various embodiments in this specification may be referred to each other.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A secondary circuit ground current monitoring system, comprising: the device comprises a control module (2), a voltage sampling module (3), a current sampling module (4), a control circuit (6), a current transformer (7), a normally closed contactor (8) and a test resistor R j ；
The voltage sampling module (3), the current sampling module (4) and the control circuit (6) are respectively connected with the control module (2), and the voltage sampling module (3) is connected with the phase A of the secondary circuit through a port A; disconnecting the original grounding point of the secondary loop, and connecting the original grounding point of the secondary loop through an N interface by the device; the device is connected with the ground through a GND port; the normally closed contactor (8) is connected between the GND port and the N interface, the current transformer (7) is arranged on a line between the GND port and the N interface, and the test resistor R j Is connected with the normally closed contactor (8) in parallel;
the control module (2) is used for calculating the capacitive current I of the grounding point in the following way 1 ：
In the formula I 1 Capacitive current as earth point, U d Is the voltage of the secondary loop to ground, Q 2 To ground current I b Phase of (2), R j To test the resistance;
when the normally closed contactor is closed, the voltage U of the secondary circuit to the ground is calculated according to the signal sent by the voltage sampling module d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1 (ii) a When the normally closed contactor is disconnected, the grounding current passes through a test resistor R j Then, the grounding current I at the moment is calculated according to the signal sent by the current sampling module b Phase Q of 2 ；
According to the voltage U of the secondary loop to the ground d The grounding current I at this time b Phase Q of 2 And a test resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 (ii) a Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1； If the current to ground is I a Capacitive current I greater than secondary loop ground 1 And judging that the secondary circuit of the circuit has a ground fault.
2. The secondary circuit ground current monitoring system according to claim 1, characterized in that each opening time of the normally closed contactor (8) is 0.5s.
3. The secondary circuit ground current monitoring system of claim 1 wherein a test resistor R j Is a 1k omega resistance.
4. The secondary circuit ground current monitoring system of claim 1, further comprising: the device comprises a touch display module (1), wherein the touch display module (1) is connected with the control module (2), and the touch display module (1) is used for displaying grounding current and fault signals and setting, recording and checking parameters of the device.
5. The secondary circuit ground current monitoring system of claim 1, further comprising: the communication module (5), the communication module (5) with the control module (2) is connected, the communication module (5) is used for sending grounding current I to the upper computer a A value of (d); and sending a fault signal to the upper computer.
6. A secondary circuit ground current monitoring method applied to the secondary circuit ground current monitoring system according to any one of claims 1 to 5, the secondary circuit ground current monitoring method comprising:
acquiring a signal sent by a voltage sampling module and a signal sent by a current sampling module, wherein the signal sent by the voltage sampling module is an analog signal of voltage between a phase line and ground of a secondary circuit, and the signal sent by the current sampling module is an analog signal of current of a grounding point of the secondary circuit;
sending a signal to a control circuit to control the normally closed contactor to be disconnected once every set time t or when the grounding current I is generated a Once disconnected when changed;
when the normally closed contactor is closed, the voltage U of the secondary circuit to the ground is calculated according to the signal sent by the voltage sampling module d Calculating the grounding current I according to the signal sent by the current sampling module a And phase Q 1 ；
When the normally closed contactor is opened, the grounding current passes through the test resistor R j Then, the grounding current I at the moment is calculated according to the signal sent by the current sampling module b Phase Q of 2 ；
According to the voltage U of the secondary loop to the ground d The grounding current I at this time b Phase Q of 2 Testing resistor R j Calculating the capacitive current I of the secondary loop grounding point 1 ；
Judging grounding current I a Whether or not it is greater than capacitive current I of secondary loop grounding point 1 ；
If the current to ground is I a Capacitor larger than secondary loop grounding pointSexual current I 1 And judging that the secondary circuit of the circuit has a ground fault.
7. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program which, when executed by a processor, implements the secondary loop ground current monitoring method according to claim 6.
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| CN104237739A (en) * | 2014-09-11 | 2014-12-24 | 深圳供电局有限公司 | Multipoint earth fault detection method, device and system for secondary current circuit |
| CN204154848U (en) * | 2014-10-28 | 2015-02-11 | 广州市仟顺电子设备有限公司 | A kind of Secondary Circuit of Potential Transformer multipoint earth faults on-Line Monitor Device |
| CN107957568A (en) * | 2017-11-23 | 2018-04-24 | 中国南方电网有限责任公司超高压输电公司柳州局 | Secondary Circuit of Potential Transformer multipoint earthing Quick positioning instrument and lookup method |
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